【摘要】 采用电喷雾电离质谱法研究了气相中4种五肽[His-Val-Phe-Arg-Lys（HK）,Ile-Tyr-Lys-Val-Glu（IE）,Val-Glu-Gly-Ile-Tyr（VY）和Ala-Thr-Leu-Leu-Ser（AS）]两两之间的非共价相互作用.将4种五肽分别以等摩尔比两两混合,配制得到6组混合溶液.质谱测试结果显示,6组混合溶液中均有配合比为1∶1的非共价复合物生成.将4种五肽按摩尔比1∶1∶1∶1混合,充分反应后,测试了竞争反应的质谱图,发现AS与VY,IE与VY反应后生成的复合物信号强度较强.采用碰撞诱导解离实验测定了复合物的结合强度,得到碰撞诱导解离残余率（SY,%）及碰撞能量曲线.碰撞能量(CE_50%)结果显示:AS-AS（12.9 eV）^HK-VY（12.8 eV）?IE-IE（18.6 eV）^HK-IE（19.7 eV）^AS-VY（20.7 eV）^IE-VY（20.3 eV）?AS-IE（23.1 eV）^VY-VY（22.3 eV）,这表明复合物的结合强度明显受到五肽中氨基酸残基侧链R基团的影响,即R基团的极性和酸碱性越强,五肽间反应得到的非共价复合物的结合强度也越强.将组成4种五肽样品的13种氨基酸分别两两混合,反应后生成复合物利用碰撞诱导解离实验测定了复合物的碰撞能量(CE_50%),得到了复合物结合强度统计图.经过分析,推断气相中五肽复合物结合的主要驱动力为氢键和静电引力.五肽分子的中间氨基酸残基上带有亲水基团氨基、羧基或羟基的容易形成非共价复合物,而带有较强疏水基团的2个五肽则不易形成共价复合物.更多还原

【Abstract】 The noncovalent interactions between two of the four pentapeptides including His-Val-Phe-Arg-Lys（ HK）,Ile-Tys-Lys-Val-Glu（ IE）,Val-Glu-Gly-Ile-Tyr（ VY） and（ Ala-Thr-Leu-Leu-Ser）（ AS） were investigated by electrospray ionization mass spectrometry. The mass spectra show the formation of 1 ∶ 1 complex by two of the four pentapeptides. The competitive reaction shows mass spectrometric signal for the complex of AS with VY and the complex of IE with VY are more stronger when the four pentapeptides were mixed together.The binding affinities of the complexes were determined by collision induced dissociation（ CID） through survival yield vs. collision energy curves. The collision energy( CE_50%) order is AS-AS（ 12. 9 eV） HK-VY（ 12. 8 eV） ? IE-IE（ 18. 6 eV） HK-IE（ 19. 7 eV） AS-VY（ 20. 7 eV） IE-VY（ 20. 3 eV） ? AS-IE（ 23. 1 eV） VY-VY（ 22. 3 eV）,indicating that the binding affinities of the complexes are apparently affected by side-chain group R of the amino acid residue composing of pentapetides,that is,the binding affinities of the complexes will be stronger with increasing the polarity and basicity of the side-chain R of amino-acid residue. The main driving force for the formation of the complexes should be ionic such as hydrogen-bonding,but not hydrophobic. The satistics of CE_50%for the complexes of amino acids which can composed of four pentapeptide samples were plotted,which further confirmed the conclusions based on CID.更多还原